U.S. patent number 5,079,202 [Application Number 07/658,738] was granted by the patent office on 1992-01-07 for catalytic cracking catalysts.
This patent grant is currently assigned to W. R. Grace & Co.-Conn.. Invention is credited to Ranjit Kumar, Alan W. Peters.
United States Patent |
5,079,202 |
Kumar , et al. |
January 7, 1992 |
Catalytic cracking catalysts
Abstract
Catalytic cracking catalysts which comprise molecular
sieves/zeolites dispersed in an inorganic oxide matrix that
includes pollucite.
Inventors: |
Kumar; Ranjit (Columbia,
MD), Peters; Alan W. (Ashton, MD) |
Assignee: |
W. R. Grace & Co.-Conn.
(New York, NY)
|
Family
ID: |
24642475 |
Appl.
No.: |
07/658,738 |
Filed: |
February 21, 1991 |
Current U.S.
Class: |
502/68; 502/243;
502/64 |
Current CPC
Class: |
B01J
23/04 (20130101); B01J 29/04 (20130101); C10G
11/05 (20130101); B01J 29/084 (20130101); B01J
2229/42 (20130101) |
Current International
Class: |
B01J
23/04 (20060101); B01J 29/00 (20060101); B01J
29/08 (20060101); B01J 29/04 (20060101); C10G
11/00 (20060101); C10G 11/05 (20060101); B01J
021/16 (); B01J 029/04 () |
Field of
Search: |
;502/64,68,243 ;423/179
;208/120,118 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Dees; Carl F.
Attorney, Agent or Firm: Savage; Arthur P.
Claims
We claim:
1. A cracking catalyst composition which comprises a molecular
sieve/zeolite dispersed in an inorganic oxide matrix which contains
pollucite.
2. The composition of claim 1 wherein the pollucite is selected
from the group consisting of naturally occurring and synthetic
pollucite and mixtures thereof.
3. The composition of claim 2 wherein the pollucite has the mole
formula
and M represents H.sup.+ and metal cations, n represents the
valence charge on metal cations, and wherein the combined Na.sub.2
O and Li.sub.2 O mole content is below about 0.5.
4. The composition of claim 1 wherein the additive is naturally
occurring pollucite.
5. The composition of claim 1 which contains from about 1 to 50
weight percent pollucite.
6. The composition of claim 1 which contains from about 5 to 60
weight percent of a molecular sieve/zeolite selected from the group
comprising synthetic faujasite, ZSM, Beta SAPO, ALPO and mixtures
thereof.
7. The composition of claim 3 wherein the zeolite is ultrastable Y
zeolite.
8. The composition of claim 1 wherein the matrix comprises silica,
alumina, silica-alumina phosphorus-alumina sols and gels, clay and
mixtures thereof.
9. The composition of claim 1 wherein the catalyst is a fluid
catalytic cracking catalyst having a particle size of 20 to 150
.mu.m and a Davison attrition index of 0 to 30 DI.
Description
The present invention relates to inorganic catalytic cracking
catalyst compositions, and more specifically, to cesium containing
cracking catalysts which are particularly effective for minimizing
the production of by-product hydrogen and coke.
Catalysts which contain zeolites dispersed in an inorganic oxide
matrix are widely used in the catalytic cracking of high molecular
weight hydrocarbons.
Commercially available catalysts typically comprise a synthetic
faujasite such as zeolite Y in combination with an inorganic oxide
matrix that includes clay and silica, alumina, or silica-alumina
sol or gel binder.
During use in commercial fluid catalytic cracking (FCC) operations,
the catalyst matrix inherently produces low value products such as
hydrogen and coke at the expense of valuable products such as
gasoline and cycle oils. Furthermore, it is observed that the
catalysts undergo progressive deactivation due to thermal
decomposition and metals (V+Ni) contamination.
U.S. Pat. No. 4,430,200 describes catalytic cracking catalysts
which contain presteamed zeolites that are exchanged with alkali
metal ions such as sodium, potassium and cesium. The catalysts
exhibit reduced activity, aging rates and lower gas yield
properties.
U.S. Pat. No. 3,647,682 describes FCC catalysts which contain
molecular sieves such as type Y-zeolites that are fully cationized
with monovalent ions such as cesium. The catalysts are selective
for the production of olefins from saturated hydrocarbon
feedstocks.
U.S. Pat. No. 4,668,655 discloses FCC catalysts which include an
SOx emission control additive that comprises bismuth, chromium or
rare earth metal and an alkali metal such as potassium, sodium or
cesium on a refractory support.
While the prior art discloses FCC catalysts which contain cesium,
these catalysts have not been used extensively on a commercial
scale.
It is therefore an object of the present invention to provide
improved cesium containing FCC catalysts that have a particularly
high degree of activity.
It is a further object to provide highly active cesium containing
FCC catalysts at reasonable cost.
These and still further objects will become readily apparent to one
skilled in the art from the following description and detailed
specific examples.
Broadly, our invention contemplates FCC catalysts which comprise a
molecular sieve/zeolite component and an inorganic oxide matrix
which contains pollucite.
More specifically, we have found that the activity characteristics
of molecular sieve/zeolite containing FCC catalyst may be improved
by the addition of about 1 to 50 weight percent of discrete
particles of pollucite having the mole formula: (0.05 to 1 Cs.sub.2
O)(1.90/n to 0 M.sup.n O.sub.n/2).Al.sub.2 O.sub.3.4 SiO.sub.2
wherein M represents H.sup.+ and metal cations, n represents the
valence charge on metal cations, and wherein the combined Na.sub.2
O and Li.sub.2 O mole content is less then about 0.5.
Catalyst compositions of our invention preferably comprise:
(a) from about 5 to 70 wt. % molecular sieve/zeolite;
(b) from about 5 to 90 wt. % inorganic oxide matrix;
(c) from about 1 to 50 wt. % pollucite; and
(d) less than about 0.01 to 1.0 wt. % Na.sub.2 O.
The molecular sieve/zeolite component may comprise synthetic
faujasite (type Y zeolite), ZSM-5 zeolite such as ZSM-5, 20,
zeolite Beta, mordenite, SAPO, ALPO, and mixtures thereof. The
zeolite/molecular sieve component may be cation exchanged and/or
thermally and chemically treated as disclosed in U.S. Pat. No.
3,293,192, U.S. Pat. No. 3,449,070, U.S. Pat. No. 3,518,051, RE
28,629, U.S. Pat. No. 3,607,043 and U.S. Pat. No. 3,676,368.
Particularly preferred zeolite components include ultrastable Y
zeolite (USY) and rare-earth calcined type Y zeolite (CREY).
The matrix component of our catalysts comprise silica, alumina,
silica-alumina, phosphorus-alumina sols and gels and binders,
preferably in combination with clay such as kaolin, and
pollucite.
The preparation of our catalysts includes the addition of finely
divided cesium additive to an aqueous slurry of the
zeolite/molecular sieve component and inorganic oxide sol, gel or
hydrogel binder and spray drying the mixture to obtain fluidizable
catalyst particles having a size range of about 20 to 150 micro
meters wherein the zeolite/molecular sieve and cesium additive are
uniformly dispersed throughout the matrix.
Procedures for preparing catalysts to which pollucite is added are
disclosed in U.S. Pat. No. 3,957,689, Canadian 967,136, U.S. Pat.
No. 4,499,197, U.S. Pat. No. 4,542,118 and U.S. Pat. No.
4,458,023.
In a particularly preferred practice of our invention, an aqueous
slurry which contains 2 to 20 weight percent pollucite, 20 to 60
wt. % kaolin, 10 to 60 wt. % USY zeolite containing 0.2 to 1.0 wt.
% Na.sub.2 O having a unit cell 24.40 to 24.60 .ANG. and 10 to 30
wt. % aluminum chlorhydroxy polymer, such as Chlorhydrol, is spray
dried and then calcined at a temperature of 500.degree. C. to
700.degree. C. The resulting catalysts have a particle size range
of 20 to 150 micro meters, an attrition index of 0 to 30 DI (as
determined by the Davison Index method described below), an
activity of 50 MA to 85 MA (as measured by ASTM Procedure
D-3907-8), and a Na.sub.2 O content of 0.01 to 1.0 wt. %.
The Davison Index (DI) is determined as follows:
A 7.0 g sample of catalyst is screened to remove particles in the 0
to 20 micron size range. The particles above 20 microns are then
subjected to a 1 hour test in a standard Roller Particle Size
Analyzer using a hardened steel jet cup having a precision bored
orifice. An air flow of 21 liters a minute is used. The Davison
Index is calculated as follows: ##EQU1##
Preferred cesium containing additives used in the practice of the
invention includes both naturally occurring and synthetic which
typically have the mole composition (0.05 to 1 Cs.sub.2 O).(1.90/n
to 0 M.sup.n O.sub.n/2).Al.sub.2 O.sub.3.4 SiO.sub.2 wherein M
represents H.sup.+, represents the valence charge on metal cations,
and wherein the combined Na.sub.2 O and Li.sub.2 O mole content is
below about 0.5.
The FCC catalyst of our invention may be used to crack hydrocarbon
feedstocks such as gas-oil, resid and mixtures thereof at reaction
temperatures of 500.degree. C. to 600.degree. C. and regeneration
temperatures of 600.degree. C. to 850.degree. C. to obtain yields
of cracked products.
Having described the basic aspects of our invention, the following
Examples are set forth to illustrate particular embodiments:
EXAMPLE I
Catalyst Preparation
A series of catalyst compositions were prepared by combining
pollucite obtained from Carus Chemical Company, Illinois, U.S.A.,
having the composition set forth in Table A, and having an
estimated milled particle size of about 0.1 to 10 .mu.m with
kaolin, aluminum chlorhydroxide polymer having the formula Al.sub.2
(OH)5Cl.(2.5 H.sub.2 O), USY zeolite having a Na.sub.2 O content of
<1 wt. % and unit cell of 24.58 .ANG. and water to obtain an
aqueous slurry having an estimated solids content of 25 wt. %. The
slurry was spray dried to obtain microspheroidal particles having a
size range of 20 to 150 .mu.m, which were calcined at 538.degree.
C. for 2 hours. The composition of the catalyst samples and
physical properties are summarized in Table B.
TABLE A ______________________________________ Element Wt. %
______________________________________ Li .16 Na 1.27 K .03 Rb .58
Cs 25.16 Mg .023 Ca .015 Sr <.013 Ba <.022 Al 9.63 Fe .13 Cr
.009 Mn .03 Si 21.6 SO.sub.4 .91
______________________________________
TABLE B ______________________________________ Sample A B C D E
______________________________________ Pollucite (wt. %) 0 4 8 12
16 Kaolin (wt. %) 50 46 42 38 34 chlorhydroxide (wt. %) 15 15 15 15
15 polymer USY (wt. %) 35 35 35 35 35
______________________________________
EXAMPLE II
Catalyst Evaluation
The catalyst samples of Example I were evaluated for the cracking
of hydrocarbons as follows.
Samples were treated for 4 hours at 815.degree. C. in 100% steam in
a fluidized bed reacted at atmospheric pressure. They were then
tested for microactivity, below.
The results of the evaluation are summarized in Table C.
TABLE C ______________________________________ Sample A B C D E
______________________________________ MA* 58.6 63.8 67.2 68.1 68.8
H.sub.2 (wt. %) 0.086 0.067 0.060 0.059 0.057 Coke (wt. %) 2.3 2.3
2.9 3.1 3.0 ______________________________________ *Microactivity
as determined by ASTM method #D39078
* * * * *